avcodec/truemotion2: Fix integer overflow in tm2_null_res_block()

Fixes: signed integer overflow: 1111638592 - -2122219136 cannot be represented in type 'int'
Fixes: 13441/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_TRUEMOTION2_fuzzer-5732769815068672
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/truemotion2.c b/libavcodec/truemotion2.c
index 4d27f0cbfc5e1a910cea4d4f703a36fdd2e48b10..18719dae1c99e3ff96855e0ded7737eb7390a75c 100644 (file)
--- a/libavcodec/truemotion2.c
+++ b/libavcodec/truemotion2.c
@@ -600,7 +600,8 @@ static inline void tm2_null_res_block(TM2Context *ctx, AVFrame *pic, int bx, int
 {
     int i;
     int ct;
-    int left, right, diff;
+    unsigned left, right;
+    int diff;
     int deltas[16];
     TM2_INIT_POINTERS();